Method for continuously reacting saturated tertiary hydrocarbons and olefines



Jan. 6, 1948. A. A. DRAEGER ETAI,

METHOD FOR CONTINUOUSLY REAGTING SATURATED TERTIARY HYDROCARBONS A NDOLEFINES Filed Nov, 5, 1958 mvENToR.

V" ATroRNEY.

Patented Jan. 6, 1,948

METHOD V FOR CONTINUOUSLY' REACTI'NGV STURTED TERTIARY" HYDRO'CARB'NS?IZEFINE S' Arthur1 A; Draeger vand CharlescT.; Shewell, Baytown;l'Iiexavassignors` toStandard 051' DevelopmentfGompany, .acmfporation ofDelaware ApplcationiNovember5, 1938, Serial No. 238,966

TheJ-present invention yis'- Vdirectedf-to ai continu- Y ons metliocfor4 tlieproduction'-ofisaturated"hy v drocarbons by the reactionbetweensaturated hy dro carbonsfcontaining tertiary "carbon atoms-'andolenes;

It has alreadybeew proposed* ttf-take`n advanitage ofl the reactionbetween'v oleiines'andsat urated hydrocarl'aonsv such'l as"paraflifnes`l and' naphthenes, which" contain#v tertiary., carboni atomsand whichl will" hereinafter' be ref''rre'dtoY astertiary hydrocarbonsnor;V more, snecifically';v tertiary parains: to producehieherhydrocarbons 1 of" av saturated' nature lbyscausing lth'eLinitialma;

terials to react" in 4the 'presence ofiamineralpacid';

catalyst, such assulphuric acid or orthophosi-y phoric` acid. Thespecic; embodimentL oflthis' general reaction. whichis'of"greatestinterest at; the presentetime is the reaction between iso@butane and olefnesto formhydrocarbonsboiling, within the gasoline range,containing aconsidr:

able amount oiiisooctane and fractionssuitahl,

for` aviation, gasoline..

The. following. .discussion`Y fonease ofLexppsitionawilhbe,.directed tothis.

specic embodimentwith thek understanding` that.

al1` referencesto isobutaneare tovbe considered.,

apnlicable toltertiary. hydrocarbons in general..`

The, reaction. between. isobutane e and`A oleines has hithertebeencarriedY` out.. oma.. batch basis, Br1eiiy,.the,previousvpracticehasbeen Ato llfaref 3m an excess of iso-parafhiozolene' In Converti*action, chamber 1 withahe; mineral` acid,- forfxexf. ample,sulphuric.aoidhaving a strengthT ofaboute 96%,1` inwhichisobutane has beenAdissolvedton.. dispersed, Thisxeactionlchamber -Was provided: withastirrer andwas surrounded-by afjacketxin amounts; Specically, Y m

L the reaction mass:v

olecular proportionsroi isobutane to isobutylene as: high/as four to.onew have been suggested; Y

AA batch' operation of" this-r type is-H attended e with many` inherentdifficulties; To'beg-in with;

thev react-ionfisslow, and, if it:is tofbecarriedtoutf` on a commercialbasis; very large reaction Vesselse musty be employed'.l The greaterthe--size` ofthe-2- reaction vessel', however; the more acutefbecome:

10E-5 the problemsl of agitation and'temperat-ure cone trol.AFurthermore; this" procedrefafordsnofop.; portunity to the operator-forconducting th'etop eration with uniformiproportionsfoffreaction mar--`terials. For example; the ratio: o1ftiz-rtiary'hyev 5"' drocarbons toA'oleiines in thefrea'ction chamber,"y

and the ratio 'of acid "tof ol'ei-in'esE in" the' reaction chamber, varyfromthe bginningftoth'e(end-'off the process. These ratios'arenotsubject tothe` control of the operatoriand cann'otbev'aried by himto influence the char'acter'of'tle product. Another difculty Withthebatch operationiis'f that'the operator has1n`o Way-ofknowin'g what' is'-the proportion of tertiaryl hydrocarbonsto ole'- ,J fines at thek pointof introduction of the *latter'toi i Accordingly, he. is unable f to',controlthis factor so as to inuencetliecharacter of the final product.It is a recognized vfact that it is desirable to have:

ing the. batchV method to av continuous.' operation. itV Wasefoundwhenanatt'empt waslna'de to se'-l cure the desired, ratio ,ottertiarylparaflines` to olenes lby properly proportioning tl'iesfeed* stock?Vthat the process becameundesirably. expensive..A

Which-Was.,a,cooling;mediumadapted-L tofmain-f becauseof the necessityofe1iminatin gl unreacted,i

tainA 4thef reacetori Vtemperatureibelovvf-about-30 C. Ilhe olefines,vpreferably-4co-nrlposeda largely of Yisobutylenegwerefthen f edintogvtha-reaction cham;-`

paraines .from thenal moduni; According-to:A they presentv inventionthis: diiculty,F has been overcome byestablishingl a? circulating streamoi,A

bere-giraduallyffwilih @mutants-stirring., Gradualaof emulsion-ofthetertiary-paraineand-fsulphuric! addition0f..theolenes,yvas.-,dictatedby=the necesl sityiorgavoiding.- theexcessivefgeneiationoi heat;

Y inrthereactionchamber: -Stirringtservedftheipun pese, of p1.eventing-,.-stratiiication; and, ing inntheefdisipation.ofrtha-heatzof' reacticrr:liliesolefineswereegenerallyaddedinfanzamounef- 'which was equimolecularwith respect; togrther; amount.ofeisohntanef'infzthemeactionf'chamber.f, `It

has;beengsuggestedithat: thefisohutaneemayffbei employedin,amountsggreaterthan;equimoleculan acid and providingV for the`desired.l ratio# offter-f tiaryfparaines to olenes fa.t-,tl'lef-pointof- :introfduction of the latter-:intofthe-reactionfmasszby`continuously* recycling "theparalines:y whereby.-

stock: This. expedient liasrr'esultediinfaaveryl con?- siderableireduction ofth'e f-amountfo'f 10W: boilingf' 50"i tertiary zparafnes,Jwhiclimust-be removedl from the final product, and thereby has greatlycheapened the process.

In order to obtain a product which contains satisfactory amounts ofisooctane and/or aviation gasoline, While maintaining high yields, ithas been found necessary to observe certain factors carefully. The mostimportant of these factors is the maintenance of a minimum ratio oftertiary paraines to olenes at the point of intro duction of the latterinto the reaction mass. It has been found that when this ratio is below30:1 the product obtained is deficient in octane fractions to anundesirable degree. Proferably, this ratio is maintained in theneighborhood of 100:1 to 200:1. The desired ratio is obtained by DIOD-erly proportioning the recycle stock to the fresh feed, the recyclestock being composed of acid and hydrocarbons. Suitable tertiaryparafiine ,to olene ratios can be maintained by maintaining the ratio ofrecycle stock to fresh feed in excess of about :1. between 35:1 and65:1.

The ratio of tertiary paraiilnes to oleiines at the point ofintroduction of the latter, depends also upon the ratio of thesematerials in the fresh feed. It has been observed that the'lower thisratio in the fresh feed the higher must be the total ratio of tertiaryhydrocarbonsto olenes at the point of introduction of the feed in orderto produce a satisfactory product. This relation is by no means linear,but, on the contrary, is exponential. In general, suitable tertiaryparaiiine to olefine ratios at the point of introduction of the freshfeed can be obtained, with the recycle stock to fresh feed ratio asindicated above, by maintaining a ratio of tertiary hydrocarbons tooleiines in the fresh feed of at least 4:1. Experience has shown thatvery good yields of isooctane can be obtained in this emulsion type ofoperation with a ratio in the fresh feed of tertiary paraiines to olenesof 8: 1, and a total ratio of these reactants, at the point ofintroduction of the fresh feed, in excess of 80: 1.

A second factor which must be considered is the overall ratio of acid tohydrocarbons in the circulating system. It has been found that withincertain limits this ratio can be varied Without having a verysubstantial effect upon the yield of product or the nature of theproduct. In general, this ratio is satisfactory when maintained between1:3 and 3:1.

In the next place, it has been found that there must be a certainminimum ratio of acid to oleiines at the point of introduction of thelatter. This ratio is established by the volume of acid passing thepoint of feed introduction over a certain period by the volume of olenesintroduced in that Period. For a successful operation this ratio shouldbeat least 50: 1.V Preferably, for maximum octane yields, this ratioshould be in excess of 150:1. Ratios in the neighborhood of 300:1 havebeen found to yield excellent results.

In general, then, it may be stated that the process of the presentinvention is carried out by establishing a circulating stream of anemulsion of isobutane in sulphuric acid which may'have an initialstrength of Bti-100%, but which, when the system is in operation, may bemaintained at a concentration of iiD-95%, maintaining a' sub" stantialportion of the stream at a temperature ranging from about 60 F. to 1759F., this portion being termed the reaction' zone, introducing' into thestream ahead of the reaction zone, a mixture of isobutane and olenewhich should contain at least four parts (by volume) of the former toone Preferably, this ratio should be C4 cut from cracking operations.

4 part (by volume) of the latter, separating a small portion of theemulsion from the main body of the stream behind the reaction zone,allowing this small portion to settle into a lower layer of sulphuricand an upper layer of hydrocarbons, discharging the latter from thesystem and returning the former to the stream, while maintaining a ratioof recycle stock to fresh feed of at least 15: 1, by volume, a tertiaryhydrocarbon to oleflne ratio at the point of introduction of the freshfeed of at least 30:1, by volume,and an acid to olene ratio, at the samepoint, of at least 50:1, by volume, and regulating the length and/or thevelocity of the stream so as to provide a contact time under reactionconditions of from about thirty minutes to one hundred and twentyminutes. The system is operated at a pressure sufcient to maintainreactants in liquid state.

In practicing the process of the present invention it is preferred touse the reactants in as pure a state as possible. Refinery operations,however, do not yield any large supply of pure C4 olefines. The mostabundant source of these olenes is the This fraction contains aconsiderable amount of normal butane, the boiling point of which is so`close to that of the butenes that separation of the two is practicallyimpossible. j

If these refinery gases were used in a continuous process in which thedesired proportions of tertiary paraflines to olenes are obtained byproperly proportioning the feed stock, the result would be the necessityof continuously separating isobutane from butane in the nal productsince it is naturally desirable to recycle the isobutane. Thisdifficulty is overcome to a large extent by the procedure of the presentinvention, since, by retaining most of the hydrocarbons fed into thesystem in the circulating system, and thereby reducing the ratio oftertiary parailine to oleflnerequired in the fresh feed, the overallamount of required separation ofiso-butane from normal butane is greatlyreduced,

It is to be understood, of course, that olefines from other sources'canbe utilized. For example, butene polymers or copolymers of butene andisobutene may be employed. Likewise, the use of propylene and `arnyleneis contemplated, either alone or in admixture. with eachother or withbutenes. Also, it may be mentioned that other isoparafns, such asisopentane and isohexane, can be used in addition to or instead ofisobutane.

The method of the present invention may be better understood from thefollowing detailed description of the accompanying drawing in` thesingle figure of which is shown schematically a front elevation of aplant suitable for the production of gasoline from isobutane andbutylene according to the present invention.

Referring to the drawing, numeral I designates a pipe which may beconsidered a closed circulatory systemr in which is arranged a pair oftowers 2, each of which is provided with perforated plates 3 which serveto effect a thorough mixing of the acid and hydrocarbons. A by-pass 4 isarranged between the two towers so that, if desired, the mixture mayonly be passed through one tower in the event that this is sufficient toprovide the proper time of contact. It is to be understood, of course,that the number of towers may be increased in order to provvide propertime of contact.

At a point behind the reaction towers 2, line l is provided with a valve5 ahead of which ls a branch line 6 provided with a valve '1. Line 6leads to a settllngrtank# 8e whlch-is provided at its uppen-end with adraw-off.r line 9 for hydro@g oarborn'prodncts. and-Y at:v its lowerend` with. a draw-off lineal for acid. The-hydrocarbon productswithdrawn. are. treated in the, usual manner, that is,washedrwitlrcaustictocomplete neutralization,stabilizedandfractionated;V

Line I0 returns to line I, and is provided with a branch line I Icontrolled by a valve I2 which is utilized for the introduction of freshacid or make-up acid into the system. Behind return line I0, in line I,is a line I 3 provided with a valve I4 for the introduction ofhydrocarbons into the feed stock. At a point adjacent the point ofintroduction of hydrocarbon feed stock is arranged a pump I5 for keepingthe stream of acid in circulation.

Line I is provided with a cooling coil I6, and line I3 is provided witha cooling coil I1 for the purpose hereinafter speci'ed.

In placing the aforedescribed system in operation the system is firstfilled with iso-butane. Sulphuric acid of a strength of between about96% and 100% is then continuously added with the concurrent withdrawalof hydrocarbons until the desired amount of sulphuric acid is containedin the system, The reverse procedure may also be used, or a preformedmixture of sulphuric acid and iso-butane may be used to ll the system.The resulting mixture of sulphuric acid and isobutane is circulated andthe addition of fresh acid through line II is begun. Concurrently withthe addition of fresh feed, hydrocarbons are withdrawn from the systemthrough line 9 in an amount sufficient to balance the amount ofhydrocarbons fed in.

In order to control the temperature of the Vcirculating stream, suitablecooling of the emulsion and of the fresh feed is effected in coolingcoils I6 and I1. It is to be understood that it is not necessary to keepthe whole stream at reaction temperature, it being suiiicient that asubstantial portion thereof be so maintained.

It is desirable that the velocity of the reaction stream be kept fairlyhigh so as to induce turbu- A lence into it. In this way thehydrocarbons and acid are maintained in reasonably homogeneous mixtureand better control of the reaction is provided. In other words it ispreferable that there be no substantially stagnant portions of thestream. As an example of a stream velocity suitable for good operationit may be stated that when pipe I has an internal diameter of one-halfinch, the rate of movement of the stream therein past the point ofintroduction of fresh feed should be between about one hundred and threehundred and fifty liters per hour.

For the first few hours of operation the hydrocarbons withdrawn willcontain only a relatively small amount of the desired product. After thesystem has been on stream a suicient length of time to reachequilibrium, say from three to six hours, the product withdrawn becomesfairly uniform and contains a large amount of the desired fractions, solong as the conditions heretofore enumerated are observed. It will beunderstood that from time to time it is necessary to add fresh make-upacid through line I I. Ordinarilymakeup acid is not required so long asthe acid in the system, which is reckoned both as free acid and combinedacid, retains a strength in excess of 90%.

By way of illustration, only, the following tables give the results of arun conducted under the preferred operating conditions according to 6the present invention. Inthisrun the operating; conditions and the yieldare set forth. It may be` mentioned that the olefi'neemployed` was arefinery Gif cut' containing Lol-41%: of isobutene and 20.4% of' normalbutene. In the following table, parts are byvolume:

Hours of Operation 7-24 25-48 49-72 73-96 Make-Up Acid, Vol. Per Cent onFresh Feed 2.7 3.3 3.3 Used Acid:

Titratable Acidit-y -per cent.- 96. 3 95.8 95.7 95` 5 Water .-do..-- 3.3 3. 4 3.6 3. 6 Effective Strength ..do. 96. 6 96.6 96. 5 96. 4 AverageReactor Temperature..o F.- 67 68 68 67 Time of Contact Minutes-. 86 9295 88 Isobutane-Butene ratio in fresh i'eed... 8:1 Recycle Ratio (Vol.Acid-Oil Mixture per Vol. Fresh Feed) l 51:1 50:1 54:1 53:1 Acid-OilRatio (at point of feed lnlet). 51:49 51:49 50:50 53:47 Acid-ButeneRatio (at point of feed inlet) 306 1 Isobutane-Butene Ratio (at point offeed inlet) 187 1 Product Yield, Per Cent on Butenes.. 159 173 1 161Inspections of Product:

ravity.. A. P. I-- 67. 9 67.3 67. 9 68.4 I. B. P-- F.. 122 130 F. B.P.-..- F.- 432 424 off at F-. 225 224 Analysis of Product byDistillation:

Butane per cent.. l. 1 1. 3 Light Fraction.... 12. 2 9. 4 9.9 OctaneFraction. 74.2 77. 8 79. 9 Heavy Fraction 12. 5 11. 5 10. 2 Inspectionof Octane F a Octane Number. 93. 5 93. 9 B. 207 206 F. B. P 254 254 50%o at V F.- 223 223 Gravity A. P. I.- 68.3 68.4 Product Yield, Per Centon Butenes (C4 Free):

Total Product 161 Octane Fraction 121 Composition of Butane FreeProduct:

Light Fraction.. per cent.. 12. 3 Octane Fraction. 75.1 Heavy Fraction.12.6

The nature and objects of the present invention having been thusdescribed and illustrated,

what is claimed as new and useful and is desired to be secured byLetters Patent is:

In the continuous alkylation of isoparain hydrocarbons by reaction witholefin hydrocarbons in the presence of a liquid alkylation catalyst ofgreater density than the hydrocarbons undergoing treatment, the stepscomprising continuously introducing feed hydrocarbons and catalyst to avertical reaction vessel, continuously withdrawing from the upperportion of said vessel a stream of mixed catalyst and hydrocarbonsincluding alkylated hydrocarbons, diverting at least a substantialportion of the withdrawn stream, recycling said diverted portion to thelower portion of said reaction vessel in such amount and undersuchvelocity of ow as to impart substantial agitation to the uidcontents of said vessel, passing the knon-diverted portion of saidstream to a settling vessel, effecting separation in said vessel betweenalkylated hydrocarbons and catalyst, separately discharging thealkylated hydrocarbons and catalyst from the separating vessel, andrecycling at least a portion of said discharged catalyst to the reactionvessel.

ARTHUR A. DRAEGER. CHARLES T. SHEWELL.

REFERENCES CITED Number Name Date 2,112,847 Ipatiei et al Apr. 5, 1938(Other references on following page) Number Name Date Ipateff et al Apr.5, 1938 Ipatieff May 21, 1935 Egloff July 23, 1935 Morrell Aug. 15, 1939Goldsby et a1. Aug. 13, 1940 OTHER REFERENCES Trade-Mark, 376,688, April2, 1940.

